During the next year, we intend to concentrate on the following goals: 1. Prepare reconstituted histone core-DNA complexes, utilizing both sequentially digestion and DNA-histone crosslinking we shall examine the specificity and arrangement of DNA interaction with the histone core. 2. Attempt to reconstitute "minichromosomes" from histone cores (with and without H1 added) and pBR322 plasmid DNA molecules. We shall examine the physical properties and specificity of nucleosome spacing on these structures. 3. Follow up on our recent observation that yeast chromatin has an unusual spacer structure (involving a 5 bp interval) to see whether this is a common feature of "active" chromatin regions. Gel hybridization techniques will be utilized. 4. Continuation of studies of transcription and transcribing regions in yeast, utilizing in vitro transcription of yeast nuclei, examination of the nuclease sensitivity of specific genes in activated and inactivated states, and measurements of the degree of acetylation of yeast histones in growing and stationary yeast cells.